The archenemy of the Atom (Ray Palmer), Chronos started his career as petty thief David Clinton, who attributed his consistent incarceration to his timing, or lack thereof. To improve his timing, he studied the rhythm of time pieces and by practice he learned to synchronize each of his actions with the beat of the prison clock. By the end of his sentence he had developed an extraordinary sense of timing which he resolved to use to further his criminal career. He then adopted the colorful costume and alter ego of Chronos, the Time Thief. Clinton had acquired an unhealthy fascination with time and he developed a series of gimmickweapons and deathtraps based on time pieces (clocks with blades as hands, flying sun dials). He liked to give time related puns, such as "Time is golden!" when spraying golden gas at Green Lantern.[1]

Chronos made his debut in Ivy Town, but was defeated by the Atom when he tried to steal an atomic clock because of an idea ironically given to him by Ray Palmer. He came close to deducing the Atom's secret identity when he realised the Atom attacked him soon after Ray saw him, and succeeded in capturing the Atom and placing him inside a watch. The Atom escaped the watch while Chronos was breaking into a vault, and used a trick to make him think he was wrong. However he escaped from jail by adapting a guard's watch, making the ticks so loud they broke open his cell door. He next tried to steal a collection of historic Hungarian clocks which each had a gem hidden inside, but was again defeated. The Atom has since thwarted all of Chronos' plans. Each appearance or new crime prompted an evolution in Chronos' weaponry. His study of time led to more intricate and revolutionary inventions—lenses that prevent people from seeing certain events (e.g. his getaway vehicle or another specific object), circuitry embedded in his costume that could control the local flow of time (freezing people in time or altering his own perception of time), an hourglass of concentrated time that could speed points up briefly and even make bricks next to a bank vault crumble in a few seconds, and ultimately a fully functional time machine (before it and the designs were destroyed). One story suggests that Chronos may have been receiving help from a future version of himself, but it is unknown at what relative time frame that Chronos came from. Another story, published in World's Finest Comics #321 (1985), suggests that Chronos made the transition from a mere thief with a time gimmick to a full-fledged time traveler after becoming acquainted with the mysterious Dr. Fox (perhaps named after Gardner Fox), a criminal scientist who had never been apprehended and who was described by Chronos as "the greatest mind since Einstein." Pre-Crisis Chronos was a member of the Crime Champions, a trio of Earth-1 villains who teamed up with a trio of Earth-2 villains to commit robberies, then escape to the other world using a vibratory device the Fiddler accidentally discovered. Chronos is able to escape Wonder Woman, Batman and Green Lantern after stealing a million dollars from the Powers City Bank. When the Earth-2 Crime Champions impersonate the Earth-1 Crime Champions, the Icicle impersonates Chronos with the help of the Wizard's Tibetan magic, and fought Batman, Wonder Woman and Green Lantern, making them touch rubber, animal, and glass as part of a spell to trap the JLA. On Earth-2 Chronos tries to steal a rare clock from a lighthouse, and uses his vibratory watch to put Aquaman into a coma, but Superman is able to revive Aquaman and captures Chronos, crushing his watch. The JLA and JSA are captured again and magically placed in cages in space, but with the aid of the Green Lanterns escape and return to Earth. Chronos tries to help the Fiddler find an Earth-3 with his chronological knowledge, but is defeated by the Martian Manhunter and Black Canary.

Chronos eventually stopped stealing for his own gain and began stealing to finance his time research. The Atom had always thwarted Chronos, but he had decided to turn his back on humanity and had retreated to a peaceful seclusion with a group of six-inch tall aliens in the Amazonianjungle. Chronos had more success without the Atom, but he brought himself to the attention of the Blue Beetle when he tried to blackmail one of the employees of Kord Inc.[2] He also fought the Beetle during Darkseid's anti-hero riots. During one struggle against the Beetle, Chronos was hurled 100 million years into the past where he encountered a time-lost Captain Atom. He later met a time traveling Superman who Chronos manipulated into helping him get home.

Upon his return to the present, Chronos was able to use his technology to manipulate the money markets to amass a fortune. However, Chronos's illegal endeavors were discovered and he was returned to prison. He was freed by the Calendar Man to work with the Time Foes, but was captured by the Teen Titans. Out of desperation and humiliation, Chronos took a drastic chance — he accepted an offer from the demon Neron and exchanged his soul for the metahuman ability to travel through time. However bargains with Neron are never fair and Chronos found that each journey through the timestream accelerated his aging. A man who should have been a healthy adult became an aged senior citizen. Clinton's efforts to bypass this flaw - passing his artificial age onto youths with a special glove of his own creation and intercepting other time travelers in an attempt to acquire their technology - brought him briefly into conflict with the Legion of Super-Heroes, in a somewhat confusing and often non-linear sequence of events.

All the experiments and Neron's "gift" had taken a toll on Clinton's body and he began to lose touch with any sense of the "now." He had trouble staying localized in time and appeared to fade away into nothingness. His disappearance was enough for him to be declared dead and speculation has suggested that he may have slipped into "The Void" of time. A funeral of sorts was held and his research was passed on to the second Chronos (Walker Gabriel).

Time travel being what it is, David Clinton's legal death has not meant the end of his presence in the DC universe; he has made several appearances since, such as during the Identity Crisis, when he claimed to have traveled forward from a point in time shortly before his final disappearance. This foreknowledge of his own (suspected) demise led to a somewhat subdued, even morose, demeanor.

In The All-New Atom #12, it was revealed that the wacky Anagram guy that has been testing and helping Ryan Choi (The New Atom) is none other than Chronos himself. In issue #20, he is revealed as the mastermind behind all of the strange occurrences surrounding Ivy Town since the start of the series. His vengeful goal is to destroy everything that Ray Palmer loved.[1]

He's able to do so by joining forces with Lady Chronos, a new companion and lover who once was Jia, Ryan's love interest in their college years. With Jia's intimate knowledge about Ryan, he was able to add a further layer of credibility to his ruse, faking years of correspondence and epistular friendship between Ryan and Ray Palmer, spurring Ryan to follow in Palmer's footsteps only to disgrace him in the eyes of Ivy Town, shaming the Atom's legacy forever.

With some help from the real Ray Palmer, Ryan is eventually able to overcome the couple, and prevent David and Jia from messing again with Ivy Town.[3] They retreat into the timestream, where they are noticed by Starro the Conqueror who, after being thwarted in his attempts to gain total domination over time by enslaving Rip Hunter and his Time Masters, retaliates by dominating Chronos' and Lady Chronos' minds, using them to travel in time and put Booster Gold against Rip, eradicating the Time Masters.[4]

In The New 52 (a 2011 reboot of the DC Comics universe), David Clinton is an agent of A.R.G.U.S. who specializes in time travel. He was tasked with finding Booster Gold after the events of Justice League International Annual #1 (October 2012). However, he had apparently failed his mission and was captured by the as-yet-unidentified leader of the newly formed Secret Society of Super Villains. Green Arrow discovers him as a captive while pursuing Professor Ivo. Professor Ivo states that the engine that Chronos is stuck in is activated. Chronos causes a temporal neutral field to envelope the manor, causing it to freeze in place throughout time, while the earth turns....which means that the Earth moves, not the manor. Thanks to the coins that the Secret Society have been given, they are able to stay within the manor without issue, but the Justice League of America is going to face a very painful death if they do not leave the house soon. Chronos was eventually rescued by the Justice League of America.[5]

Walker Gabriel got possession of Clinton's research after his death. He became the second Chronos and was the lead character of a short-lived comic book series published by DC Comics, acting as both a hero and a criminal depending on circumstances, and often running afoul of the Linear Men. He was eventually revealed to be the son of a temporal theorist who had worked with Clinton and created Chronopolis, the city beyond time. The series ran for 12 issues (including a DC One Million crossover numbered 1,000,000) between March 1998 and February 1999, and concluded with Gabriel wiping himself from history, to save his mother's life. The nature of Chronopolis, however, meant he still existed despite not being born. Still, due to an unclear series of events, it appeared in fact two Walker Gabriels existed: one outside of time, one within it, but only up to the point when he removed himself out of it. After that, the timeline streamlined and only the timetraveling Chronos remained. Gabriel had many encounters with members of the Linear Men and also met Destiny of the Endless during this series.[6]

Gabriel briefly appeared in the pages of JSA (2005); there, he was killed by Per Degaton when he was struck by a car a decade before receiving his time-travel powers; however, as is the case when Degaton's adventures end in failure, his death was reversed.

Gabriel most recently had a cameo in "Superman Beyond 3D" #1 as an inhabitant of Limbo.

Jia, a young Chinese woman from Hong Kong, was the longtime sweetheart of the young and socially awkward Ryan Choi, a stereotypical nerd more interested in science than a social life. Eventually, Jia and Ryan parted, and she ended up marrying the local football jock, Alvin, a guy who at high school did his best to make Ryan's life miserable.

Ryan Choi, now an American teacher and the new Atom, at Ivy University, was contacted again by Jia, claiming that her husband, who had died in unclear circumstances, had resurfaced as an undead being who was harassing and stalking her. Ryan, still carrying a torch for Jia, returned to Hong Kong to fight the menace of Alvin, and his undead gang of bullies.

There Alvin revealed how Jia herself had brutally killed him, and she was far from being the helpless woman she pretended to be to rekindle her relationship with Ryan. They parted again.

Sometime after that, Jia came into possession of Clinton's research, and became the third Chronos, or later Lady Chronos. Wearing a female version of the classic Clinton's outfit, she allied with Clinton in his attempt to destroy Ivy Town and ruin the Atom's reputation for good. Using her knowledge about Ryan, she helped Chronos into faking a mail correspondence with Ryan, giving him the shrinking belt he eventually used to become the Atom, but planting the seeds of his downfall, trapping part of the denizens of Ivy Town in a microverse held in strange viral constructs hidden in Ryan's bloodstream.

With some help from the former Atom, Ray Palmer, Ryan dodged the bullet, but still feels responsible for Jia's wrongdoings.

Jia claims that Dwarfstar, master assassin and shrinking nemesis of Ryan, is her "firstborn". Whether she's speaking literally, or metaphorically as both men got their powers by her actions, remains to be seen.[7]

Lady Chronos is later seen as a mind-controlled pawn of Starro the Conqueror, along with Chronos. During her battle against Booster Gold for ensuring Starro's domination of the timestream, she reveals to know with a certain degree of intimacy the future adventures of Booster and his sister Goldstar, having observed and interacted with them.[8]

The David Clinton incarnation of Chronos appears in the two-part Justice League Unlimitedanimated series episode "The Once and Future Thing" voiced by Peter MacNicol. A meek physics professor from the Batman Beyond era, he was ostracized by his peers for his theories on time travel but secretly perfected a time-traveling device in the form of a belt. Aware of the problems of time paradoxes, he uses the device to add to his collection of rare artifacts, stealing the items from the past at the points when they would no longer be missed (e.g. Cleopatra's comb, an early draft of the Magna Carta, etc.). However, when his wife Enid Clinton (voiced by Mindy Sterling) learns of this, she scolds him for not using the belt to become rich. Eventually, her incessant hectoring drove him to retreat into the past. While trying to steal Batman's utility belt, he attracts the attention of Batman, Wonder Woman and Green Lantern so he tries to escape and they follow him and are accidentally pulled into the Old West. In the time between his arrival and theirs, Clinton's time belt was stolen by local villain Tobias Manning and used it to steal future technology and take over the town. After the three League members as well as several Western heroes (consisting of Jonah Hex, Bat Lash, El Diablo and Ohiyesa Smith) defeat Manning, Clinton tricked Batman into enabling him to get the belt and retreated into his time. Now power-hungry and increasingly unstable, he makes himself "the undisputed master of space and time" while adopting his Chronos identity. After following Chronos to the Batman Beyond era, the three Leaguers discover that his trips through time have severely impacted the timeline; the Titanic and the Leaning Tower of Pisa are situated alongside Gotham's architecture, amongst other bizarre things. The three Leaguers also find that Chronos has allied with the third brand of the Jokerz. Chronos's irresponsible actions are causing time to collapse. After Wonder Woman was erased from existence, Batman and Green Lantern team up with the remaining roster of the JLU: Warhawk, Static, Batman II and the future version of Bruce Wayne. Now fearful, Enid leads the combined Justice League to the Old West jail that Chronos had brought to the future where he slept every night (presumably because his six months in the jail cell were a vacation away from his nagging wife and far more comfortable to him). After a pitched battle where Static and Batman II are killed and Warhawk barely survived, only Batman, Green Lantern and Chronos are left incapacitated. As time begins to fall apart all around them, Chronos escapes into the timestream intending to return to the beginning of time to reset and make himself into a god. When the two heroes catch up with him, Batman inserts a disc into Chronos's belt that reverses everything that had happened just before they reach the Beginning. With the timeline restored, Green Lantern and Batman return to the present day (retaining the memories of their experience but Wonder Woman does not) while Clinton himself is stuck in a permanent time-loop of the last few seconds of his life before the whole chain started, which happens to be his wife Enid berating him for all eternity (a laGroundhog Day). Although he is depicted as an arch-enemy to Ray Palmer (also appearing in the series) in the comics, they never met each other in this interpretation.

Chronos appears in the Batman: The Brave and the Bold episode "Sword of the Atom!". He has returned to attack the city causing Batman and Ryan Choi to look for Ray Palmer. By the end of the episode, Batman, Ryan Choi, and Aquaman end up fighting Chronos while Ray Palmer stays with the Kartathians.

Chronos appears as a recurring antagonist in Legends of Tomorrow, played by Dominic Purcell and Jordan Davis, with the character's voice provided by Steve Blum. He is a temporal bounty hunter, employed by the Time Masters to capture Rip Hunter, who went rogue and is leading a team on an unauthorized mission to prevent Vandal Savage from conquering the world. In "Left Behind", it is revealed that Chronos is an older version of Heat Wave / Mick Rory, a former member of the team. Rory had betrayed them to a band of space pirates which led to his being marooned by his former partner, Leonard Snart / Captain Cold. Found barely alive by the Time Masters, he was brought to Vanishing Point and trained by them to be their agent. When tasked to capture Hunter's team, Rory eagerly accepted. However, he is ultimately defeated by the team and imprisoned on their ship, the Waverider, in the hope of rehabilitating their former teammate. Eventually making peace with the rest of the team, Rory notes during a confrontation with another assassin for the Time Masters that he cannot be considered a traitor as he was only ever on his side rather than the Time Masters'. The Masters attempt to re-initiate Rory as Chronos when the team are recaptured by the Time Masters, but he fakes succumbing to his brainwashing so that he can escape and take action against their enemies.

The David Clinton incarnation of Chronos appears in Justice League Action episode "Time Share," voiced by Andy Richter. Batman and Blue Beetle follow him into the past to make sure that Batman doesn't survive his first fight with Carmine Falcone. Upon Blue Beetle spilling his Chrono Bombs enough to slow down the past Batman, Carmine Falcone, and his men, Batman fights Chronos while Blue Beetle works to redirect the gunfire from the guns of Carmine Falcone's men. Upon Carmine Falcone and his men being defeated by the past Batman, the present Batman and Blue Beetle return to the present and hand Chronos over to the police.

Chronos makes an appearance in issue #22 of the TV series-based SuperFriends comic.[9]

In an issue of Justice League Adventures (adapted from Justice League) titled "Wolf's Clothing," Chronos (not the latter version in Justice League Unlimited) apparently captured Superman, Batman and Wonder Woman in a single moment of time and plots to auction them off to the highest bidding villain. However, this plan was later revealed to be an elaborate 'sting' operation set up by the Justice League to capture most of their villains, with 'Chronos' actually Batman in disguise and the other League members also disguised as various villains at the auction. In another issue called "The Moment", after Chronos is released from prison due to the intervention of his future self and a recorded message from the future Superman confirming that Chronos has reformed, Flash and Atom discover that he's traveled to the past to prevent the death of his brother Bobby in a fire, but his interference (to the point that multiple versions of him keep traveling back in time to the same moment to try and change history) threatens to wreck the timestream, forcing them to bring his brother into his future to convince Chronos to move on from his death.